Jet perforating gun



Oct. 9, 1962 J. E. BROWN JET PERFORATING GUN 2 Sheets-Sheet 1 Filed May 5, 1959 FIG. 2.

FIG. I.

W E L L F LU l D INVENTOR. JACK E. BROWN,

:mmrnl Oct. 9, 1962 J. E. BROWN .JET PERFORATING GUN 2 Sheets-Sheet 2 Filed May 5, 1959 FIG. 4.

INVENTOR. JACK E. BROWN,

ATTORNEY-S.

United States Patent Ofiice 3,057,297 Patented Oct. 9, 1962 3,057,297 JET PERFORATING GUN Jack E. Brown, Houston, Tex., assignor to Halliburton Company, a corporation of Delaware Filed May 5, 1959, Ser. No. 811,150 1 Claim. (Cl. 102-21.8)

This invention relates to a jet perforating gun for perforating wells, and more particularly to the construc tion of a jet perforating gun which will minimize the tendency of the gun to jump in the well upon firing.

Jet perforating guns for wells utilizing the Monroe effect are well known. These guns conventionally employ a plurality of shaped charges which when fired cause the gun to jump in the well. This jump may be as much as 150 feet on occasions. Upon jumping, the wire line on which the gun is suspended may kink, birdcage a section of the cable, or even tie a knot in the cable necessitating splicing of the cable before it is used again at the injured section. Even more serious, the gun, which weighs several hundred pounds, may part the line or pull out of the rope socket upon falling free after jumping in the well.

It is believed that the reason the gun jumps in the well is the rapid movement and expansion of the large volumes of gas generated by firing of the several shaped charges. As this gas expands, it tends to move the gun.

Desirably, the gun should be held against jumping and it is an object of this invention to provide a jet perforating gun with means for counteracting the tendency of the gun to jump upon firing.

Another object is to utilize the high gas pressure of the shaped charges in a manner to resist the tendency of the gun to jump.

Other objects, features and advantages of this inven tion will be apparent from the specification, drawings and claim.

In carrying out the objects of this invention, one or more upwardly directed openings are provided in the housing of the gun to permit upward escape of gases from the housing upon firing of the charges. The reaction force from this upwardly escaping gas urges the gun downwardly and counteracts the tendency of the gun to jump in the well upon firing.

In the drawings, wherein there is shown by way of illustration several embodiments of this invention, and wherein like reference numerals indicate like parts- FIGURE 1 is a view in vertical cross-section through a well and a gun constructed in accordance with this invention;

FIGURE 2 is a fragmentary view of the gun of FIGURE 1 in elevation with parts broken away to illustrate flow of gases upon firing of the charges;

FIGURE 3 is a view in vertical cross-section through a bull plug constructed in accordance with this invention and adapted to be used to close the lower end of the tubular housing of the jet gun shown in FIGURE 1;

FIGURE 4 is a view in vertical cross-section through a sub for interconnecting two parts of the tubular housing of a gun body as shown in FIGURES 1 and 3 and provided with upwardly directed openings in accordance with this invention; and

FIGURE 5 is a view along the line 5-5 of FIGURE 4.

Referring now to the drawings, the gun includes an elongated housing adapted to be suspended in a well from one end. The housing may be provided by a tubular body closed at its lower end by a plug 49 as shown in FIGURE 3, and at its upper end by an upper sub 12. Inasmuch as the interior of the housing is desirably kept free from the fluid within the well, the plug 49 seals with the body 10 by means of 0 rings 52 to provide interiorly thereof a sealed chamber 13. For loading reasons, at least one of the end closures should be easily removable, and for this reason the upper sub is threadedly connected to the housing by the thread system 16.

In accordance with this invention, one or more upwardly directed openings are provided in the elongated housing, and preferably they are provided in the upper sub 12 by a plurality of openings 17. These openings should be symmetrically arranged about the upper sub so that gas escaping through the openings will result in a substantially pure downward component of force on the gun and not cause it to kick sideways in the well.

It is customary to fire these charges while the guns are submerged in the well fluids to reduce the amount of jump of the gun upon firing of the charges. To exclude this liquid from the interior of the gun, a seal disc 18 should be provided in each of the upwardly directed openings 17. The disc preferably seats against a shoulder 19 (FIGURE 2) provided by a counterbore 21 in the opening 17 and seals against fluid outside of the gun from passing into the gun, no matter what the degree of differential between internal and external pressure. The seal disc is free to move outwardly and clear the opening 17 upon an increase in pressure within the housing, caused by firing of the charges, to a value greater than ambient pressure. This will permit the gases generated upon firing within the housing to escape in an upward direction through the openings 17 in the manner shown in FIGURE 2. The upwardly escaping gases, of course, result in a'reactive downward force on the gun which resists the tendency of the gun to jump in the well.

A plurality of shaped charges 22 are positioned in the tubular body 10 in the conventional manner. Preferably, they are spaced vertically from each other and arranged to fire through helically arranged ports 23 in body 10. In the housing illustrated, the body 10 is provided with a recess 24 opposite each port 23 and the rear end of the shaped charge 22 is positioned in the recess during assembly and held in this position by an alignment sleeve 25 which is threadedly received in the port 23 and bears against the front of the shaped charge to fix it in place. This bushing may be of the frangible type which disintegrates upon firing of the shaped charges. It is desirable to both exclude fluids from the chamber 13 and from the conical front (not shown) of each shaped charge. While the bushing 25 could provide a seal between the body 10 and shaped charge 22 to exclude fluid from the chamber 13, it is preferred to provide a seal disc 26 in the port 23 to isolate both the chamber 13 and the front of the shaped charge from well fluids until the gun is fired. The disc 26 is threaded into port 23 and seats upon a shoulder 27 in the port 23 and seals against a pressure condition in which the exterior pressure is greater than the interior pressure. However, the jet produced by detonation of shaped charge 22 perforates the disc 26, which is thereby rupted to open the port 23.

The several shaped charges are fired by a Primacord 28 which is in turn fired by a firing assembly '29. The firing assembly may be of any conventional type, and is here shown to include an electrically fired detonating cap 31 which is arranged immediately above the upper end of Primacord 28. Upon detonating of the cap the Primacord is detonated.

In the form of gun illustrated the upper sub .12 has a portion 12a which is slidably received within a lower cylindrical extension 32 of the firing assembly housing 33. Desirably, a seal is provided between these parts by O-ring '34. A nut 35 is made up on the upper sub through the thread assembly 36. When the nut and upper sub are fully made up a shoulder 37 on the firing assembly housing is engaged by the nut to suspend the upper sub a from the firing assembly housing. The firing assembly housing is in turn suspended from a rope socket 38 on the lower end of the suspending and firing cable 39.

The firing assembly is positioned within a bore 41 and a counterbore 42 in the firing assembly housing, and includes a bushing 43 and the electrically fired detonating cap 31. The detonating cap makes electrical connection with the firing cable 39 through means not shown.

In preparing the gun for use, the upper sub and tubular body are separated and the several jet charges and Primacord snaked into position within the body It). The shaped charges are locked in position with the sleeves 25 and thereafter the upper sub 12 made up with the tubular body. The detonating cap 31 ispositioned in the firing assembly, and the bushing 43 made up within the firing assembly housing to position the detonating cap 31. Thereafter, the nut 35 is made up on the upper end of the upper sub to complete the assembly. At any time after the shaped charges are in position, the seal disc 26 may be positioned in the ports 23. The seal disc 18 which closes the upwardly directed opening 17 is placed in position before operating the gun.

In operation, the gun is lowered on cable 39 to the desired elevation in the well, and the gun is fired by an electrical impulse through cable 39. This impulse fires the detonating cap 31, which is turn actuates the Primacord 28. Upon actuation of Primacord 28, all of the shaped charges are fired almost instantaneously to perforate the casing 44 in the manner illustrated in FIGURE 2. Upon firing of the shaped charges, a large amount of gas is generated within the housing of the gun and, in accordance with this invention, at least a portion of this generated gas is permitted to escape through the upwardly directed openings 17. The reactive force of this escaping gas tends to urge the gun downwardly, and to counteract the tendency of the gun to jump in the hole upon firing.

As is well known, guns of this type may be of considable length, and it is conventional to interconnect sections of the tubular housing by an intermediate sub such as shown in FIGURE 4. For purposes of ease in loading the shaped charges in the gun, it is preferred to threadedly interconnect the housing and sub and seal therebetween by the upper and lower O-rings 45 and 46, respectively.

If desired, an equalizing bore 47 may extend through the intermediate sub 40 to equalize pressure above and below the sub.

In accordance with this invention, one or more upwardly directed openings 48 are provided in the intermediate sub. These openings are closed, in the manner previously explained, by disc 18.

Of course, upon firing of the gun, gas generaed by firing of the charges will be permitted to escape in an upwardly direction through theopenings 48, and result in a re active downward force on the gun which will minimize its tendency to jump.

Referring now to FIGURE 3, there is shown a -forrn of bull plug 49 which may be used to seal the lower end of the gun. For purposes of ease in loading the gun, the bull plug may be threadedly connected to the housing 10 by the thread system 51 and sealingly secured thereto by the seals 52. A central bore 53 extends downwardly from the upper end of the bull plug and communicates with a plurality of upwardly directed openings 54. These openings provide for the upward escape of gas from the lower end of the gun to provide a reactant downward force on the gun in the manner previously explained. These openings may also be sealed by the seal disc 18 in the manner previously explained.

It will be apparent from the above explanation of this invention that the upwardly directed openings for permitting escape of gas from within the housing could be provided in any portion of the housing. As it is desirable to direct these openings at a relatively small angle from the vertical or longitudinal central axis of the gun, they are preferably provided in one of the subs. It will be further apparent that these openings could be provided by either the upper, lower or intermediate sub, or by any combination thereof.

The foregoing disclosure and description of the invention is illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claim without departing from the spirit of the invention.

What is claimed is:

A jet perforating gun comprising:

(a) an elongated housing adapted to be suspended in a Well, said housing including a tubular body and means closing the tubular body at both ends;

(11) a plurality of shaped charges;

(0) means mounting said shaped charges in said housing in position to fire their jets outwardly through the walls of said tubular body to perforate the well;

(d) means for firing said shaped charges;

(:2) at least one of the means closing the tubular body at its ends being a removable plug;

(1) means sealing said plug in said tubular body;

(g) said plug providing an upwardly directed opening communicating the interior of said housing with the exterior, and further providing a counterbore in the outer end of said opening having a transverse shoulder at the inner end of the counterbore;

(h) a disk in said counterbore seated on said shoulder to seal said opening against intrusion of well tfluids; and

(i) a cable attached to said housing for suspending the latter in a well;

(j) said disk being ejectable outwardly from said counterbore by gas within said housing under pressure produced essentially by the firing of said plurality of shaped charges to free said opening, whereby gas in said housing is released through said opening in an upward direction to counteract the tendency of the gun to jump upon firing.

References Cited in the file of this patent UNITED STATES PATENTS 1,582,184 Mims Apr. 27, 1926 2,029,478 Haines Feb. 4, 1936 2,279,676 Hart Apr. 14, 1942 2,616,370 Foster Nov. 4, 1952 2,742,857 Turechek Apr. 24, 1956 2,749,841 Jones June 12, 1956 2,915,011 Hamill Dec. 1, 1959 

